JP2018104788A - Electrochemical hydrogen pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrochemical hydrogen pump capable of reducing the possibility of breaking an electrolyte membrane due to a pressure difference between a cathode and an anode. A voltage applicator 13 applies a voltage between an anode and a cathode of a membrane electrode assembly 15. Next, when the anode gas is supplied to the anode chamber 8 through the anode inlet pipe 11, hydrogen in the anode gas releases electrons on the anode to become protons. The liberated electrons move to the cathode via the voltage applicator. On the other hand, the protons penetrate the electrolyte membrane 4 while entraining water molecules and come into contact with the cathode. At the cathode, a reduction reaction is performed by the protons that have passed through the electrolyte membrane and the electrons from the cathode gas diffusion layer 2C, and cathode gas (H2) is generated. Thereby, impurities such as CO2 gas are removed in the membrane electrode assembly. [Selection diagram] Figure 2

Description

  The present disclosure relates to an electrochemical hydrogen pump.

  In recent years, hydrogen has attracted attention as a clean alternative energy source to replace fossil fuels due to environmental problems such as global warming and energy problems such as the depletion of petroleum resources. When hydrogen burns, only water is released, and carbon dioxide and nitrogen oxides that cause global warming are not discharged. Therefore, hydrogen is expected as clean energy. As an apparatus using hydrogen as a fuel, for example, there is a fuel cell, and the development and popularization of a fuel cell is progressing for a power source for automobiles and a private power generation for home use. In the coming hydrogen society, not only the production of hydrogen, but also the development of technology capable of storing hydrogen at a high density and transporting or using it at a low capacity and at a low cost is required. Furthermore, in order to promote the spread of fuel cells, it is necessary to improve the fuel supply infrastructure. Accordingly, various proposals have been made to purify and boost high-purity hydrogen.

  For example, in Patent Document 1, as shown in FIG. 12, an electrolyte membrane support member 30 of an electrochemical cell for high differential pressure is used as a gas diffusion layer in contact with the electrolyte membrane. That is, a plurality of rectangular recesses are formed on one surface of the support member 30, and a plurality of rhombus recesses are formed on the other surface. And the overlapping part of both recessed parts comprises the through-hole 31 through which the fluid passes. This can prevent clogging of the fluid flow path, which may occur in the conventional mesh type gas diffusion layer, and can secure rigidity capable of withstanding the differential pressure between the high pressure side and the low pressure side of the electrochemical cell. Therefore, deformation that reaches the breakage point of the electrolyte membrane is suppressed by the support of the support member 30.

  Further, in Patent Document 2, as shown in FIG. 13, these diffusion plates are arranged so that the centers of the openings of the gas diffusion plate 112 and the gas diffusion plate 113 adjacent to each other in the stacking direction of the separator of the fuel cell are shifted. A configuration is proposed. Thereby, the gas diffusibility of the separator of a fuel cell can be improved.

Japanese Patent No. 4733380 JP 2008-2335060 A

  However, Patent Document 1 does not sufficiently examine the breakage of the electrolyte membrane when the electrolyte membrane is pressed on the through hole of the gas diffusion layer due to the differential pressure between the high pressure side and the low pressure side of the electrochemical cell. Further, since Patent Document 2 is intended for a gas diffusion plate of a separator of a fuel cell, the problem of breakage of the electrolyte membrane when the electrolyte membrane is pressed on the opening of the gas diffusion plate is not assumed.

  One aspect of the present disclosure has been made in view of such circumstances, and the possibility that the electrolyte membrane pressed against the anode gas diffusion layer is broken by the differential pressure between the cathode and the anode is higher than in the past. An electrochemical hydrogen pump that can be reduced is provided.

  In order to solve the above problems, an electrochemical hydrogen pump according to an aspect of the present disclosure includes an electrolyte membrane including a pair of main surfaces, a cathode catalyst layer provided on one main surface of the electrolyte membrane, and the electrolyte membrane. An anode catalyst layer provided on the other main surface; a cathode gas diffusion layer provided on the cathode catalyst layer; an anode gas diffusion layer provided on the anode catalyst layer; the cathode catalyst layer and the anode catalyst layer; A voltage applicator for applying a voltage between the anode gas diffusion layer and the anode gas diffusion layer, wherein the anode gas diffusion layer includes a laminate of a plurality of metal sheets provided with a plurality of air holes. The arrangement positions of the plurality of ventilation holes of the first metal sheet adjacent to the catalyst layer are shifted from the arrangement positions of the plurality of ventilation holes of the second metal sheet adjacent to the first metal sheet, A part of the opening of the vent hole of the first metal sheet overlaps with the opening of the vent hole of the second metal sheet, and the remaining part of the opening of the vent hole of the first metal sheet is the second part. The metal sheet is closed by a region where no air hole is provided.

  The electrochemical hydrogen pump according to an aspect of the present disclosure has an effect that the possibility that the electrolyte membrane pressed against the anode gas diffusion layer is broken by the differential pressure between the cathode and the anode can be reduced as compared with the conventional case.

FIG. 1 is a cross-sectional view of an example of an electrolyte membrane pressed by a differential pressure between a cathode and an anode of an electrochemical hydrogen pump on a vent hole of an anode gas diffusion layer. FIG. 2 is a diagram illustrating an example of the electrochemical hydrogen pump according to the first embodiment. FIG. 3 is a diagram illustrating an example of an anode gas diffusion layer of the electrochemical hydrogen pump according to the first embodiment. FIG. 4 is a plan view of an example of an anode gas diffusion layer of an electrochemical hydrogen pump according to a first modification of the first embodiment. FIG. 5 is a diagram illustrating an example of a cathode gas diffusion layer of an electrochemical hydrogen pump according to a second modification of the first embodiment. FIG. 6 is a plan view of an example of the cathode gas diffusion layer of the electrochemical hydrogen pump according to the second modification of the first embodiment. FIG. 7A is a cross-sectional view of an example of an anode gas diffusion layer of the electrochemical hydrogen pump according to the second embodiment. FIG. 7B is a cross-sectional view of an example of an anode gas diffusion layer of the electrochemical hydrogen pump according to the second embodiment. FIG. 8A is a plan view of an example of a metal sheet of a laminate of anode gas diffusion layers. FIG. 8B is a plan view of an example of a metal sheet of a laminate of anode gas diffusion layers. FIG. 8C is a plan view of an example of a metal sheet of a laminate of anode gas diffusion layers. FIG. 9 is a cross-sectional view of an example of the anode gas diffusion layer of the electrochemical hydrogen pump according to the first example of the second embodiment. FIG. 10 is a cross-sectional view of an example of the anode gas diffusion layer of the electrochemical hydrogen pump according to the second example of the second embodiment. FIG. 11 is a cross-sectional view of an example of an anode gas diffusion layer of an electrochemical hydrogen pump according to a modification of the second embodiment. FIG. 12 is a diagram showing an example of a conventional gas diffusion layer. FIG. 13 is a diagram illustrating an example of a conventional gas diffusion layer.

  As a result of intensive investigations on the rupture of the electrolyte membrane when the electrolyte membrane is pressed on the vent of the anode gas diffusion layer by the pressure difference between the cathode and the anode of the electrochemical hydrogen pump, the following findings were obtained.

  For example, as shown in FIG. 1, when the electrolyte membrane 104 is pressed on the vent hole 125 of the anode gas diffusion layer 102A due to the above-described differential pressure, the flexible electrolyte membrane 104 is separated from the anode gas diffusion layer 102A. The air hole 125 hangs down in a concave shape. Then, the electrolyte membrane 104 is bent at the edge portion 125E of the vent hole 125, so that cracks or the like may occur in the electrolyte membrane 104 at the edge portion 125E, and the electrolyte membrane 104 may be broken.

  Here, as the vent hole 125 is processed more finely, even if the electrolyte membrane 104 is pressed on the vent hole 125, the amount of sag of the electrolyte membrane 104 in the vent hole 125 can be reduced, so that the electrolyte membrane 104 is less likely to break. Become. However, such fine processing of the air holes 125 may be difficult for the anode gas diffusion layer 102A. For example, as the hole diameter of the vent hole 125 decreases, the variation in the hole diameter of the vent hole 125 tends to increase. Further, the processing cost of the vent hole 125 tends to increase as the hole diameter of the vent hole 125 decreases.

  Therefore, the electrochemical hydrogen pump according to the first aspect of the present disclosure has been devised based on the above knowledge, and is provided on an electrolyte membrane having a pair of main surfaces and one main surface of the electrolyte membrane. A cathode catalyst layer, an anode catalyst layer provided on the other main surface of the electrolyte membrane, a cathode gas diffusion layer provided on the cathode catalyst layer, an anode gas diffusion layer provided on the anode catalyst layer, and a cathode catalyst A voltage applicator for applying a voltage between the anode catalyst layer and the anode catalyst layer, wherein the anode gas diffusion layer includes a laminate of a plurality of metal sheets provided with a plurality of vent holes, and in the anode gas diffusion layer The arrangement positions of the plurality of vent holes of the first metal sheet adjacent to the anode catalyst layer are shifted from the arrangement positions of the plurality of vent holes of the second metal sheet adjacent to the first metal sheet, First metal sheet A part of the opening of the second metal sheet overlaps with the opening of the second metal sheet, and the remaining part of the opening of the first metal sheet is formed by the second metal sheet. It is blocked by a region that is not provided.

  According to such a configuration, the electrochemical hydrogen pump of this aspect can reduce the possibility that the electrolyte membrane pressed against the anode gas diffusion layer will break due to the differential pressure between the cathode and the anode.

  Specifically, the first metal sheet vent hole and the second metal sheet vent hole are displaced so that a part of both vent holes overlap, The amount of sag of the electrolyte membrane in the vent hole of the first metal sheet can be reduced without performing fine processing of the vent hole on one metal sheet. That is, even if the electrolyte membrane is pressed on the vent hole of the first metal sheet, the electrolyte membrane can be held in the region where the vent hole of the second metal sheet is not provided. In the air holes, the electrolyte membrane is appropriately suppressed from sagging beyond the second metal sheet. Thereby, even if the electrolyte membrane is pressed on the vent hole of the first metal sheet due to the differential pressure between the cathode and the anode of the electrochemical hydrogen pump, the electrolyte membrane is prevented from being bent at the edge portion of the vent hole. As a result, the electrolyte membrane is less likely to break.

  In the gas diffusion layer described in Patent Document 1, the concave portion on the first side surface and the concave portion on the second side surface are asymmetric, and a part of the concave portion on the first side surface is not formed on the concave portion on the second side surface. Although closed, this gas diffusion layer is an integral gas diffusion layer, that is, a single sheet. As described above, in Patent Document 1, when a plurality of integrated gas diffusion layers are stacked like the gas diffusion layer of the present disclosure, the integrated gas diffusion layer in which the concave portion on the first side surface and the concave portion on the second side surface overlap each other. The gas channel is not blocked by a region where the gas channel of another adjacent integrated gas diffusion layer is not formed. Therefore, the electrochemical hydrogen pump according to the first aspect of the present disclosure can reduce the possibility that the electrolyte membrane breaks compared to the invention of Patent Document 1.

  In the electrochemical hydrogen pump according to the second aspect of the present disclosure, the thickness of the first metal sheet may be smaller than the thickness of the electrolyte membrane in the electrochemical hydrogen pump according to the first aspect.

  According to this configuration, the sagging of the electrolyte membrane in the vent hole of the first metal sheet is regulated by the thickness of the first metal sheet, and the sagging amount is smaller than the thickness of the electrolyte membrane. Therefore, the electrochemical hydrogen pump of this aspect can reduce the amount of sag of the electrolyte membrane in the vent hole of the first metal sheet compared to the case where the thicknesses of both are opposite. Accordingly, even if the electrolyte membrane is pressed on the vent hole of the first metal sheet due to the differential pressure between the cathode and the anode of the electrochemical hydrogen pump, the electrolyte membrane is further bent at the edge portion of the vent hole. It can be effectively suppressed.

The electrochemical hydrogen pump according to the third aspect of the present disclosure is the electrochemical hydrogen pump according to the first aspect or the second aspect, wherein the opening of the vent hole of the first metal sheet and the vent hole of the second metal sheet are provided. area of the portion where the opening overlap, 8 × pi × (tensile strength of the electrolyte membrane) × (thickness of the electrolyte membrane) ^2/3 × (theoretical fracture pressure of the electrolyte membrane) × (3+ (Poisson's ratio of the electrolyte membrane) ) May be smaller.

  According to such a configuration, the area of the portion where the opening of the vent hole of the first metal sheet and the opening of the vent hole of the second metal sheet overlap can be appropriately set.

  The electrochemical hydrogen pump according to the fourth aspect of the present disclosure is the electrochemical hydrogen pump according to any one of the first aspect to the third aspect, wherein the cathode gas diffusion layer includes a plurality of vent holes. A fourth metal comprising a laminate of metal sheets, wherein at least some of the openings of the plurality of vent holes of the third metal sheet adjacent to the cathode catalyst layer in the cathode gas diffusion layer are adjacent to the third metal sheet; The total area of the sheet that is blocked by the region where the plurality of vent holes is not provided is that, in the anode gas diffusion layer, the openings of the plurality of vent holes of the first metal sheet are the plurality of the second metal sheet. It may be smaller than the total area covered by the region where the air holes are not provided.

  The electrochemical hydrogen pump according to the fifth aspect of the present disclosure is the electrochemical hydrogen pump according to any one of the first aspect to the third aspect, wherein the cathode gas diffusion layer includes a plurality of vent holes. The cathode gas diffusion layer includes a laminate of metal sheets, and among the plurality of vent holes of the third metal sheet adjacent to the cathode catalyst layer, at least part of the opening is adjacent to the third metal sheet. The number of the vent holes of the third metal sheet, which is blocked by the region where the plurality of vent holes of the metal sheet of 4 are not provided, is the number of the vent holes of the first metal sheet in the anode gas diffusion layer. In addition, at least a part of the opening may be smaller than the number of vent holes of the first metal sheet that is blocked by a region where the plurality of vent holes of the second metal sheet are not provided.

  When the ventilation hole of the metal sheet is blocked, the gas diffusibility of the cathode gas diffusion layer is lowered. Here, since the cathode gas diffusion layer is less susceptible to deformation due to the differential pressure between the cathode and anode of the electrochemical hydrogen pump than the anode gas diffusion layer, the electrochemical hydrogen pump of the fourth and fifth aspects is not used. By comprising as mentioned above, the fall of the gas diffusibility of a cathode gas diffusion layer is reduced compared with the case where a cathode gas diffusion layer is comprised similarly to an anode gas diffusion layer.

  The electrochemical hydrogen pump according to the sixth aspect of the present disclosure is the electrochemical hydrogen pump according to any one of the first aspect to the fifth aspect, in which at least one of the plurality of metal sheets includes through holes. There may be provided a communication path for communicating.

  According to such a configuration, the electrochemical hydrogen pump of this aspect can diffuse the anode gas more uniformly than in the past. In other words, the metal sheet of the laminate of the anode gas diffusion layer includes a communication path, so that the anode gas passing through the anode gas diffusion layer can be sent not only in one direction but also in any direction from an appropriate flow path member. it can. Then, the direction of the anode gas flow in the anode gas diffusion layer can be arbitrarily set by laminating metal sheets having different communication path arrangement patterns. Thereby, the gas diffusibility of the anode gas diffusion layer is improved.

  Further, for example, in the case of adopting a configuration in which the anode gas is allowed to flow into the through hole of the laminate of the anode gas diffusion layer through the gas flow path of an appropriate flow path member, There is a risk that the anode gas does not flow into the through hole of the laminate of the anode gas diffusion layer located on the vertical line of the part where the gas flow path of the member is not provided, and the gas diffusion of the anode gas diffusion layer may become non-uniform. is there. However, in the anode gas diffusion layer of the electrochemical hydrogen pump according to this aspect, the anode gas can also flow through the through-holes of the laminate of the anode gas diffusion layer via the communication path. It is possible to suppress non-uniform gas diffusion in the diffusion layer.

  The electrochemical hydrogen pump according to the seventh aspect of the present disclosure is the electrochemical hydrogen pump according to the sixth aspect, wherein the communication path is provided in the same metal sheet adjacent to the metal sheet provided with the communication path. The formed through holes may be communicated with each other.

  The electrochemical hydrogen pump according to the eighth aspect of the present disclosure is the electrochemical hydrogen pump according to the sixth aspect or the seventh aspect, wherein the communication path is adjacent to the metal sheet provided with the communication path. You may connect the through-holes provided in the metal sheet.

  The laminate of the anode gas diffusion layer is provided with the above communication path, so that the anode gas passing through the laminate is sent not only in the direction penetrating the laminate but also in the direction parallel to the main surface of the laminate. Can do. Therefore, the gas diffusibility of the anode gas diffusion layer is improved.

  Further, the electrochemical hydrogen pump according to the ninth aspect of the present disclosure is the electrochemical hydrogen pump according to any one of the first aspect to the eighth aspect, in which the laminate of the anode gas diffusion layer is a metal firing that diffuses gas. It may also include a bonded metal sheet.

  According to such a configuration, the electrochemical hydrogen pump according to this aspect includes the anode gas diffusion layer stack including the metal sheet of the metal sintered body, and the stack does not include the metal sheet of the metal sintered body. Compared with the case of a plurality of metal steel plates provided with ventilation holes, it is easier to ensure the gas permeability and gas diffusion properties required for the anode gas diffusion layer.

  Hereinafter, specific examples of the above aspects of the present disclosure will be described with reference to the accompanying drawings. Each of the specific examples described below shows an example of each of the above aspects. Therefore, the shapes, materials, constituent elements, arrangement positions of the constituent elements, connection forms, and the like shown below do not limit each of the above aspects unless otherwise stated in the claims. In addition, among the following constituent elements, constituent elements that are not described in the independent claims indicating the highest concept of this aspect are described as optional constituent elements. In the drawings, the same reference numerals are sometimes omitted. In addition, the drawings schematically show each component for easy understanding, and there are cases where the shape and dimensional ratio are not accurately displayed.

(First embodiment)
[Device configuration]
FIG. 2 is a diagram illustrating an example of the electrochemical hydrogen pump according to the first embodiment.

  The electrochemical hydrogen pump 16 includes a membrane electrode assembly 15 (hereinafter referred to as MEA 15), a first plate 1A, a second plate 1C, and a voltage applicator 13. The MEA 15 includes an electrolyte membrane 4, a cathode catalyst layer 3C, an anode catalyst layer 3A, a cathode gas diffusion layer 2C, and an anode gas diffusion layer 2A, and these layers are joined in a stacked state.

The electrolyte membrane 4 includes a pair of main surfaces. The electrolyte membrane 4 is a proton conductive polymer membrane that can transmit protons (H ⁺ ). The electrolyte membrane 4 may be any membrane as long as it is a proton conductive polymer membrane. For example, examples of the electrolyte membrane 4 include a fluorine-based polymer electrolyte membrane. Specifically, as the electrolyte membrane 4, for example, Nafion (registered trademark, manufactured by DuPont), Aciplex (trade name, manufactured by Asahi Kasei Co., Ltd.) or the like can be used.

  The cathode catalyst layer 3 </ b> C is provided on one main surface of the electrolyte membrane 4. The cathode catalyst layer 3C includes, for example, platinum as a catalyst metal, but is not limited thereto.

  The anode catalyst layer 3 </ b> A is provided on the other main surface of the electrolyte membrane 4. The anode catalyst layer 3A includes, for example, RuIrFeOx as a catalyst metal, but is not limited thereto.

  The cathode catalyst layer 3C and the anode catalyst layer 3A are not particularly limited because various methods can be used as the catalyst preparation method. For example, examples of the catalyst carrier include conductive porous material powder and carbon-based powder. Examples of the carbon-based powder include powders such as graphite, carbon black, and activated carbon having electrical conductivity. The method for supporting platinum or other catalytic metals on a carrier such as carbon is not particularly limited. For example, a method such as powder mixing or liquid phase mixing may be used. Examples of the latter liquid phase mixing include a method of dispersing and adsorbing a carrier such as carbon in a catalyst component colloid liquid. If necessary, platinum or other catalytic metals can be supported in the same manner as described above using the active oxygen removing material as a carrier. The state of the catalyst metal such as platinum supported on the carrier is not particularly limited. For example, the catalyst metal may be finely divided and supported on the carrier with high dispersion.

  The cathode gas diffusion layer 2C is provided on the cathode catalyst layer 3C. The cathode gas diffusion layer 2C may be composed of, for example, a highly elastic graphitized carbon fiber, or a porous body in which the surface of a titanium powder sintered body is subjected to platinum plating, or a paper-like one. Can be used. When the former graphitized carbon fiber is used, when the carbon fiber is heat-treated at, for example, 2000 ° C. or more, graphite crystals develop and change to graphite fibers. Further, the cathode gas diffusion layer 2C may be constituted by, for example, a laminate of a plurality of metal sheets. A specific configuration of the metal sheet laminate will be described in a second modification.

  The anode gas diffusion layer 2A is provided on the anode catalyst layer 3A. The anode gas diffusion layer 2A needs to be rigid enough to withstand the pressing of the electrolyte membrane 4 due to the differential pressure between the cathode and anode of the electrochemical hydrogen pump 16. The anode gas diffusion layer 2A may have any configuration as long as the anode gas diffusion layer 2A has sufficient rigidity to withstand the pressing of the electrolyte membrane 4 due to the differential pressure. The anode gas diffusion layer 2A is composed of, for example, a laminate of a plurality of metal sheets, and the specific configuration will be described later.

  The first plate 1A (separator plate) is provided with a gas flow path 14A through which anode gas flows. That is, the first plate 1A is a member for supplying the anode gas to the anode gas diffusion layer 2A. Specifically, the first plate 1A has, for example, a serpentine-shaped gas flow path 14A communicating with a manifold (not shown) in plan view, and the formation region of the gas flow path 14A is the anode gas diffusion layer 2A. It arrange | positions so that it may contact | abut to the main surface.

  Since the electrolyte membrane 4 not only has a high membrane resistance (IR loss) and a reaction resistance (reaction overvoltage) when hydrogen is dissociated into protons and electrons when dried, the electrolyte membrane 4 may be easily broken. Includes at least hydrogen gas and water molecules (water vapor). Examples of the anode gas include a hydrogen-containing reformed gas and a hydrogen-containing gas generated by a water electrolysis method.

  The second plate 1C (separator plate) is provided with a gas flow path 14C through which the cathode gas flows. That is, the cathode gas from the cathode gas diffusion layer 2C flows through the gas flow path 14C of the second plate 1C. Specifically, the second plate 1C has, for example, a serpentine-shaped gas flow path 14C communicating with a manifold (not shown) in a plan view, and a region where the gas flow path 14C is formed is a cathode gas diffusion layer 2C. It arrange | positions so that it may contact | abut to the main surface. Examples of the cathode gas include high-purity hydrogen gas.

  A single cell of the electrochemical hydrogen pump 16 is configured by sandwiching the upper and lower surfaces of the MEA 15 with the first plate 1A and the second plate 1C, respectively.

  The voltage applicator 13 applies a voltage between the cathode catalyst layer 3C and the anode catalyst layer 3A. Specifically, the high potential side terminal of the voltage applicator 13 is connected to the conductive first plate 1A, and the low potential side terminal of the voltage applicator 13 is connected to the conductive second plate 1C. . The voltage applicator 13 may have any configuration as long as a voltage can be applied between the cathode catalyst layer 3C and the anode catalyst layer 3A.

  Here, the cathode gas diffusion layer 2 </ b> C and the anode gas diffusion layer 2 </ b> A are power feeding bodies in the cathode and anode of the MEA 15, respectively. That is, the cathode gas diffusion layer 2C and the anode gas diffusion layer 2A have a role of energizing between the first plate 1A and the second plate 1C and the cathode catalyst layer 3C and the anode catalyst layer 3A.

  The cathode gas diffusion layer 2C and the anode gas diffusion layer 2A are gasses between the gas flow path 14A of the first plate 1A and the gas flow path 14C of the second plate 1C, and the cathode catalyst layer 3C and the anode catalyst layer 3A. It also has the role of spreading. For example, the anode gas flowing through the gas flow path 14A of the first plate 1A diffuses to the surface of the anode catalyst layer 3A through the anode gas diffusion layer 2A.

  If necessary, a single cell of the electrochemical hydrogen pump 16 may be provided with a cooler or the like, and a stack composed of a plurality of single cells may be configured by stacking two or more cells.

  As shown in FIG. 2, the electrochemical hydrogen pump 16 includes an anode chamber 8 and a cathode chamber 7.

  The inside of the anode chamber 8 communicates with the anode inlet pipe 11 and also communicates with the gas flow path 14A of the first plate 1A via a fluid flow path (for example, a pipe, a manifold, etc.) not shown. Thus, the anode gas flowing through the anode inlet pipe 11 flows into the anode chamber 8 and is then supplied to the gas flow path 14A of the first plate 1A.

  The inside of the cathode chamber 7 communicates with the cathode outlet pipe 12 and also communicates with the gas flow path 14C of the second plate 1C via a fluid flow path (for example, a pipe, a manifold, etc.) not shown. Thus, the cathode gas (hydrogen gas) that has passed through the MEA 15 flows through the gas flow path 14C of the second plate 1C, flows into the cathode chamber 7, and then is supplied to the cathode outlet pipe 12. The cathode outlet pipe 12 is provided with an on-off valve 9 (for example, an electromagnetic valve), and the cathode gas is stored in the high-pressure hydrogen tank 10 by opening and closing the on-off valve 9 in a timely manner. And such cathode gas is used for the fuel of the hydrogen utilization apparatus (for example, fuel cell) which is not illustrated.

[Configuration of anode gas diffusion layer]
FIG. 3 is a diagram illustrating an example of an anode gas diffusion layer of the electrochemical hydrogen pump according to the first embodiment. FIG. 3A shows a perspective view of the anode gas diffusion layer 2A. FIG. 3B shows a plan view of a partial region 100 of the gas diffusion portion 50 of the anode gas diffusion layer 2A. In FIG. 3C, a cross section of the CC portion in the region 100 of the gas diffusion portion 50 of the anode gas diffusion layer 2 </ b> A is shown together with the electrolyte membrane 4.

  As shown in FIG. 3A, the anode gas diffusion layer 2A includes a laminate 20 of a plurality of metal sheets 22 provided with a plurality of vent holes (not shown in FIG. 3A). In FIG. 3A, the plurality of metal sheets 22 are illustrated in a separated state, but in reality, the metal sheets 22 are laminated. For example, the metal sheet 22 may be integrally joined by welding, welding, brazing, or the like. In this case, the main surface of the laminated metal sheet 22 may be surface bonded by diffusion bonding or the like.

  The metal sheet 22 is configured such that portions other than the air holes do not have gas permeability. For example, the metal sheet 22 may be a metal steel plate having a thickness of about several tens of μm to several hundreds of μm (for example, about 100 μm), but is not limited thereto. The metal sheet 22 can be manufactured, for example, by performing metal casting and rolling. Since the metal casting and rolling processes are known, a detailed description is omitted.

  Here, as shown in FIGS. 3B and 3C, in the anode gas diffusion layer 2A, the arrangement positions of the plurality of vent holes 25F of the first metal sheet 22F adjacent to the anode catalyst layer 3A The arrangement positions of the plurality of vent holes 25S of the second metal sheet 22S adjacent to the first metal sheet 22F are shifted. Further, a part of the opening of the vent hole 25F of the first metal sheet 22F overlaps with the opening of the vent hole 25S of the second metal sheet 22S. Further, the remaining portion of the opening of the vent hole 25F of the first metal sheet 22F is closed by a region where the vent hole 25S of the second metal sheet 22S is not provided.

  In the first metal sheet 22F, for example, a plurality of vent holes 25F may be formed at equal intervals in the vertical and horizontal directions. In the horizontal arrangement of the vent holes 25F adjacent to the vertical direction of the vent holes 25F, the horizontal position of the vent holes 25F is shifted by 1/2 of the interval L between the vent holes 25F adjacent in the horizontal direction. May be. The shape of the vent hole 25F may be any shape. The vent hole 25F may be a round hole having a diameter of about several tens of μm, for example. As a material of the first metal sheet 22F, for example, stainless steel or titanium can be used, but is not limited thereto.

  The second metal sheet 22S may be formed with a plurality of vent holes 25S vertically and horizontally at the same pitch as the vent holes 25F. In the horizontal arrangement of the vent holes 25S adjacent in the vertical direction of the vent holes 25S, the horizontal position of the vent holes 25S is shifted by 1/2 of the interval L between the vent holes 25S adjacent in the horizontal direction. It may be. The shape of the vent 25S may be any shape. The vent hole 25S may be a round hole having a diameter of about several tens of μm, for example. The diameter of the vent hole 25F may be equal to the diameter of the vent hole 25S. As a material of the second metal sheet 22S, for example, stainless steel or titanium can be used, but is not limited thereto.

  In the electrochemical hydrogen pump 16 of the present embodiment, when the first metal sheet 22F and the second metal sheet 22S are stacked, the position of the vent hole 25F of the first metal sheet 22F and the second position are arranged. The positions of the air holes 25S in the metal sheet 22S are parallel to the main surfaces of the first metal sheet 22F and the second metal sheet 22S, and a part of both the air holes 25F and 25S It is shifted so as to overlap.

  As a result, a portion 27A (dot portion in FIG. 3B) where the opening of the vent hole 25F of the first metal sheet 22F and the opening of the vent hole 25S of the second metal sheet 22S overlap each other in plan view is the first. The metal sheet 22F and the second metal sheet 22S are formed as leaf-shaped ventilation spaces.

  During operation (operation) of the electrochemical hydrogen pump 16, the electrolyte membrane 4 is pressed on the vent hole 25F of the first metal sheet 22F by the differential pressure between the cathode and the anode. As shown in FIG. 3 (c), the air hole 25F hangs in a concave shape. However, in the electrochemical hydrogen pump 16 of the present embodiment, the electrolyte membrane 4 is held in a region where the vent holes 25S of the second metal sheet 22S are not provided, and the thickness Y of the first metal sheet 22F is It is smaller than the thickness X of the electrolyte membrane 4. Therefore, the sagging of the electrolyte membrane 4 in the vent hole 25F of the first metal sheet 22F is regulated by the thickness Y of the first metal sheet 22F, and the sagging amount is smaller than the thickness X of the electrolyte membrane 4.

  The overlapping portion 27A may have any shape as long as it is formed as a ventilation space where a part of the ventilation hole 25F and the ventilation hole 25S overlap. In this example, a part of the circular vent hole 25F and a part of the circular vent hole 25S overlap each other to form a leaf-shaped vent space in plan view, but the present invention is not limited to this. For example, a circular ventilation space may be formed in plan view by overlapping the ends of the elliptical ventilation holes in the longitudinal direction.

  A method for setting the size (area) of the overlapping portion 27A will be described in an embodiment. The configuration of the metal sheet 22 of the laminate 20 other than the first metal sheet 22F and the second metal sheet 22S will be described in the second embodiment.

  In addition, the shape, arrangement | positioning, dimension, etc. of the ventilation hole 25F of the above 1st metal sheet 22F and the ventilation hole 25S of the 2nd metal sheet 22S are illustrations, Comprising: It is not limited to this example.

[Operation]
Hereinafter, the operation of the electrochemical hydrogen pump of the embodiment will be described with reference to the drawings. Part or all of the following operations may be performed by a control program of a controller (not shown). The controller may have any configuration as long as it has a control function. The controller includes, for example, an arithmetic circuit and a storage circuit that stores a control program. Examples of the arithmetic circuit include an MPU and a CPU. An example of the memory circuit is a memory. The controller may be composed of a single controller that performs centralized control, or may be composed of a plurality of controllers that perform distributed control in cooperation with each other.

  First, a voltage is applied between the anode and cathode of the MEA 15 by the voltage applicator 13.

Next, when anode gas is supplied to the anode chamber 8 through the anode inlet pipe 11, hydrogen in the anode gas releases electrons on the anode and becomes protons (H ⁺ ) (formula (1)). The liberated electrons move to the cathode via the voltage applicator 13.

  On the other hand, protons permeate the electrolyte membrane 4 with water molecules and touch the cathode. At the cathode, a reduction reaction is performed by protons that have permeated through the electrolyte membrane 4 and electrons from the cathode gas diffusion layer 2C to generate cathode gas (hydrogen gas) (formula (2)).

Thereby, gas purification is performed with high efficiency from the anode gas containing impurities such as CO ₂ gas. That is, impurities such as CO ₂ gas are removed in the MEA 15. The anode gas sometimes contains CO gas as an impurity. In this case, since CO gas reduces the catalytic activity of the anode catalyst layer 3A and the like, it is better to remove the CO gas with a CO remover (not shown) (for example, a converter, a CO selective oxidizer, etc.).

  When the on-off valve 9 is closed, the pressure of the cathode gas in the cathode chamber 7 increases and the gas pressure at the cathode becomes high. Specifically, the relationship among the anode gas pressure P1, the cathode gas pressure P2, and the voltage E of the voltage applicator 13 is formulated by the following equation (3).

Anode: H ₂ (low pressure) → 2H ⁺ + 2e ⁻ (1)
Cathode: 2H ⁺ + 2e ⁻ → H ₂ (high pressure) (2)
E = (RT / 2F) ln (P2 / P1) + ir (3)
In Equation (3), R is a gas constant (8.3145 J / K · mol), T is the temperature (K) of MEA 15, F is a Faraday constant (96485 C / mol), P2 is the gas pressure at the cathode, and P1 is the anode pressure. Gas pressure, i is current density (A / cm ² ), and r is cell resistance (Ω · cm ² ).

  From equation (3), it can be easily understood that the cathode gas pressure P2 can be increased by increasing the voltage E of the voltage applicator 13.

  Therefore, in the electrochemical hydrogen pump 16 of the present embodiment, the gas pressure at the cathode in the cathode chamber 7 is increased by closing the on-off valve 9 and increasing the voltage E of the voltage applicator 13. When the gas pressure at the cathode reaches a predetermined pressure or higher, the high-pressure hydrogen tank 10 is filled with the cathode gas in the cathode chamber 7 through the cathode outlet pipe 12 by opening the on-off valve 9. On the other hand, when the gas pressure of the cathode in the cathode chamber 7 becomes lower than a predetermined pressure, the cathode chamber 7 and the high-pressure hydrogen tank 10 are shut off by closing the on-off valve 9. For this reason, the cathode gas in the high-pressure hydrogen tank 10 is prevented from flowing back into the cathode chamber 7.

  In this way, the electrochemical hydrogen pump 16 raises the cathode gas (hydrogen gas) to a desired target pressure and fills the high-pressure hydrogen tank 10.

  At this time, a differential pressure between the cathode and the anode of the electrochemical hydrogen pump 16 is generated, and the electrolyte membrane 4 is pressed against the anode gas diffusion layer 2A by this differential pressure. The electrochemical hydrogen pump 16 of the present embodiment is The possibility that the electrolyte membrane 4 pressed against the anode gas diffusion layer 2A by the above-described differential pressure is broken can be reduced as compared with the conventional case.

  Specifically, as shown in FIG. 3B and FIG. 3C, the arrangement position of the vent hole 25F of the first metal sheet 22F and the arrangement position of the vent hole 25S of the second metal sheet 22S. Means that the vent holes 25F and the vent holes 25S are partially displaced so that they overlap each other, so that the first metal sheet 22F is not subjected to microfabrication of the first metal sheet 22F. The amount of sag of the electrolyte membrane 4 in the vent hole 25F can be reduced. That is, as shown in FIG. 3C, even when the electrolyte membrane 4 is pressed on the vent hole 25F of the first metal sheet 22F, the vent hole 25S of the second metal sheet 22S is not provided. Since the electrolyte membrane 4 can be held, the electrolyte membrane 4 is appropriately suppressed from sagging beyond the second metal sheet 22S in the vent hole 25F of the first metal sheet 22F. Thus, even if the electrolyte membrane 4 is pressed on the vent hole 25F of the first metal sheet 22F due to the differential pressure between the cathode and the anode of the electrochemical hydrogen pump 16, the electrolyte membrane is formed at the edge portion 25E of the vent hole 25F. Since the bending of 4 can be suppressed, the electrolyte membrane 4 is hardly broken.

  In addition, the electrolyte membrane 4 is held in a region where the vent hole 25S of the second metal sheet 22S is not provided, and the thickness Y of the first metal sheet 22F is smaller than the thickness X of the electrolyte membrane 4. For this reason, the sagging of the electrolyte membrane 4 in the vent hole 25F of the first metal sheet 22F is regulated by the thickness Y of the first metal sheet 22F, and the sagging amount is smaller than the thickness X of the electrolyte membrane 4. Therefore, the electrochemical hydrogen pump 16 of the present embodiment can reduce the amount of sag of the electrolyte membrane 4 in the vent hole 25F of the first metal sheet 22F, compared to the case where the thicknesses of both are opposite. Thus, even if the electrolyte membrane 4 is pressed on the vent hole 25F of the first metal sheet 22F due to the differential pressure between the cathode and the anode of the electrochemical hydrogen pump 16, the electrolyte membrane is formed at the edge portion 25E of the vent hole 25F. It can suppress more effectively that 4 is bent.

(Example)
The electrochemical hydrogen pump 16 of the example of the first embodiment is similar to the electrochemical hydrogen pump 16 of the first aspect or the second aspect in that the opening of the vent hole 25F of the first metal sheet 22F and the second metal sheet. The area of the portion 27A where the openings of the 22S vent holes 25S overlap is 8 × circularity × (tensile strength of the electrolyte membrane 4) × (film thickness of the electrolyte membrane 4) ² / (3 × (theoretical fracture of the electrolyte membrane 4) Pressure) × (3 + Poisson's ratio of electrolyte membrane 4))).

  In general, it is known that the following formula (4) is established when an electrolyte membrane is placed on an appropriate member having a circular opening and an appropriate pressure is applied.

p = 8 × γ × (2 × h / d) ² / (3 × (3 + v)) (4)
In formula (4), p is the theoretical breaking pressure of the electrolyte membrane, γ is the tensile strength of the electrolyte membrane, h is the thickness of the electrolyte membrane, d is the diameter of the circular opening, and v is the electrolyte membrane. Poisson's ratio.

  Here, the inventors have a long diameter D of the portion 27A (leaf-shaped ventilation space) where the opening of the ventilation hole 25F of the first metal sheet 22F and the opening of the ventilation hole 25S of the second metal sheet 22S overlap (FIG. 3). (B)) is assumed to be the diameter d of the equation (4), it is determined that the relationship of the equation (4) can be approximately established.

In this case, the long diameter D of the portion 27A where the opening of the vent hole 25F of the first metal sheet 22F and the opening of the vent hole 25S of the second metal sheet 22S overlap is expressed by (32 × (electrolyte membrane 4 Tensile strength) × (film thickness of the electrolyte membrane 4) ² / (3 × (theoretical breaking pressure of the electrolyte membrane 4) × (3 + Poisson's ratio of the electrolyte membrane 4))) When less than ^1/2 , the electrolyte membrane 4 It is possible to appropriately prevent the electrolyte membrane 4 from being broken at the theoretical breaking pressure. In addition, the area of the portion 27A where the opening of the vent hole 25F of the first metal sheet 22F and the opening of the vent hole 25S of the second metal sheet 22S overlap (that is, the circumferential ratio × (D / 2) ² ) is expressed by the equation From (4), 8 × circularity × (tensile strength of electrolyte membrane 4) × (film thickness of electrolyte membrane 4) ² / (3 × (theoretical breaking pressure of electrolyte membrane 4) × (3 + Poisson of electrolyte membrane 4) If the ratio is smaller than the ratio)), the electrolyte membrane 4 can be appropriately prevented from breaking at the theoretical breaking pressure of the electrolyte membrane 4. When deriving the major axis D and the area of the portion 27A where the openings overlap, the theoretical breaking pressure of the electrolyte membrane 4 may be obtained separately through experiments or the like.

  As described above, in the electrochemical hydrogen pump 16 of the present embodiment, the area of the portion 27A where the opening of the vent hole 25F of the first metal sheet 22F and the opening of the vent hole 25S of the second metal sheet 22S overlap is appropriately set. be able to.

  The electrochemical hydrogen pump 16 of the present embodiment may be the same as the electrochemical hydrogen pump 16 of the first embodiment except for the above features.

(First modification)
FIG. 4 is a plan view of an example of an anode gas diffusion layer of an electrochemical hydrogen pump according to a first modification of the first embodiment. FIG. 4 shows a plan view of a part of the gas diffusion portion 50 (see FIG. 3A) of the anode gas diffusion layer 2A.

  In the electrochemical hydrogen pump 16 of the first embodiment, the case where the vent hole 25F of the first metal sheet 22F and the vent hole 25S of the second metal sheet 22S have the same shape has been described.

  In the electrochemical hydrogen pump 16 of this modification, a case where the vent hole 125F of the first metal sheet 22F and the vent hole 125S of the second metal sheet 22S are similar to each other will be described.

  In the example shown in FIG. 4, the diameter of the circular vent hole 125F of the first metal sheet 22F is larger than the diameter of the circular vent hole 125S of the second metal sheet 22S. In this example, at three locations around the vent hole 125F of the first metal sheet 22F, a part of the opening of the vent hole 125F corresponds to each of the three vent holes 125S of the second metal sheet 22S. It overlaps with a part. Accordingly, the first portion 127AA, the second portion 127AB, and the third portion 127AC (dot portions in FIG. 4) in which the opening of the one air hole 125F and the opening of the three air holes 125S overlap each other are the first metal sheet. It is formed around the vent hole 125F of 22F with a substantially equal interval.

  The electrochemical hydrogen pump 16 of this modification may be the same as the electrochemical hydrogen pump 16 of the first embodiment or the example of the first embodiment except for the above-described features. For example, the areas of the first portion 127AA, the second portion 127AB, and the third portion 127AC may be derived based on the setting method described in the example of the first embodiment.

(Second modification)
FIG. 5 is a diagram illustrating an example of a cathode gas diffusion layer of an electrochemical hydrogen pump according to a second modification of the first embodiment. FIG. 5A shows a perspective view of the cathode gas diffusion layer 2C. FIG. 5B shows a plan view of a partial region 100 of the gas diffusion portion 50 of the cathode gas diffusion layer 2C. FIG. 5C shows a cross section of the CC section in the region 100 of the gas diffusion section 50 of the cathode gas diffusion layer 2C.

  The electrochemical hydrogen pump 16 of this modification is the same as that of the first embodiment, the example of the first embodiment, and the electrochemical hydrogen pump 16 of the first modification of the first embodiment. The cathode gas diffusion layer 2C is provided with a plurality of ventilation holes 25G of the third metal sheet 22G adjacent to the cathode catalyst layer 3C. Of the fourth metal sheet 22H adjacent to the third metal sheet 22G is covered by the area where the plurality of vent holes 25H are not provided in the anode gas diffusion layer 2A. The area where the openings of the plurality of vent holes 25F of the first metal sheet 22F are blocked by the region where the plurality of vent holes 25S of the second metal sheet 22S are not provided. Total smaller than that.

  Since the detailed configuration of the metal sheet 22 of the cathode gas diffusion layer 2C is the same as the configuration of the metal sheet 22 of the anode gas diffusion layer 2A, description thereof is omitted. The third metal sheet 22G and the fourth metal sheet 22H of the cathode gas diffusion layer 2C are anode gas diffusion except for the state in which the third metal sheet 22G and the fourth metal sheet 22H are laminated. Since it is the same as that of the structure of the 1st metal sheet 22F and the 2nd metal sheet 22S of layer 2A, description is abbreviate | omitted.

  In the electrochemical hydrogen pump 16 of this modification, when the third metal sheet 22G and the fourth metal sheet 22H are laminated, the arrangement position of the vent holes 25G of the third metal sheet 22G and the fourth metal sheet The positions of the 22H vent holes 25H are parallel to the main surfaces of the third metal sheet 22G and the fourth metal sheet 22H, and the vent holes 25G and 25H partially overlap each other. It is shifted to.

  As a result, a portion 27C (dot portion in FIG. 5B) where the opening of the vent hole 25G of the third metal sheet 22G and the opening of the vent hole 25H of the fourth metal sheet 22H overlap with each other in the plan view is the third. The metal sheet 22G and the fourth metal sheet 22H are formed as elliptical ventilation spaces.

  The size (area) of the portion 27C where the above openings overlap is such that the opening of the vent hole 25F of the first metal sheet 22F and the opening of the vent hole 25S of the second metal sheet 22S in the anode gas diffusion layer 2A. It is larger than the area of the overlapping portion 27A (dot portion in FIG. 3B). That is, as described above, the total area in which at least a part of the opening of the vent hole 25G of the third metal sheet 22G is blocked by the region where the vent hole 25H of the fourth metal sheet 22H is not provided is In the anode gas diffusion layer 2A, the opening of the vent hole 25F of the first metal sheet 22F is smaller than the total area covered by the region where the vent hole 25S of the second metal sheet 22S is not provided. .

  The overlapping portion 27C may have any shape as long as the ventilation hole 25G and the ventilation hole 25H are formed as a ventilation space. In this example, a part of the circular vent hole 25G and a part of the circular vent hole 25H overlap each other to form an elliptical vent space in plan view, but the present invention is not limited to this. For example, the circular ventilation hole 25G and the circular ventilation hole 25H may be completely overlapped to form a circular ventilation space in plan view.

  In the example shown in FIG. 6, the diameter of the circular vent hole 125G of the third metal sheet 22G is larger than the diameter of the circular vent hole 125H of the fourth metal sheet 22H. In this example, at three locations around the vent hole 125G of the third metal sheet 22G, a part of the opening of the vent hole 125G corresponds to each of the three vent holes 125H of the fourth metal sheet 22H. It overlaps with a part. Accordingly, the first portion 127CA, the second portion 127CB, and the third portion 127CC (dot portions in FIG. 6) in which the opening of the one air hole 125G overlaps the opening of the three air holes 125H are the third metal sheet. Around the 22G vent hole 125G, the air holes are formed at substantially equal intervals.

  The sizes (areas) of the first portion 127CA, the second portion 127CB, and the third portion 127CC that overlap the openings described above are each one vent hole 125F of the first metal sheet 22F in the anode gas diffusion layer 2A. Are larger than the respective areas of the first portion 127AA, the second portion 127AB, and the third portion 127AC (dot portions in FIG. 4) in which the openings of the three metal holes 22S of the second metal sheet 22S overlap. That is, as described above, the total area where at least a part of the opening of the vent hole 125G of the third metal sheet 22G is blocked by the region where the vent hole 125H of the fourth metal sheet 22H is not provided is In the anode gas diffusion layer 2A, the opening of the vent hole 125F of the first metal sheet 22F is smaller than the total area covered by the region where the vent hole 125S of the second metal sheet 22S is not provided. .

  As described above, the electrochemical hydrogen pump 16 according to the present modification can reduce a decrease in gas diffusibility of the cathode gas diffusion layer 2C as compared with the case where the cathode gas diffusion layer 2C is configured in the same manner as the anode gas diffusion layer 2A. Specifically, when the plurality of vent holes 25G and 125G of the third metal sheet 22G are closed, the gas diffusibility of the cathode gas diffusion layer 2C is lowered. Here, the cathode gas diffusion layer 2C is less susceptible to deformation due to the differential pressure between the cathode and anode of the electrochemical hydrogen pump 16 than the anode gas diffusion layer 2A. For this reason, the total of the areas where the openings of the vent holes 25G and 125G in the cathode gas diffusion layer 2C are blocked by the regions where the vent holes 25H and 125H are not provided is defined as the vent holes 25F and 2F in the anode gas diffusion layer 2A. By making the opening of 125F smaller than the total area covered by the region where the vent holes 25S and 125S are not provided, the reduction in gas diffusibility of the cathode gas diffusion layer 2C is reduced.

  The shape and arrangement of the vent holes 25G and 125G of the third metal sheet 22G and the vent holes 25H and 125H of the fourth metal sheet 22H are merely examples, and are not limited to this example.

  The electrochemical hydrogen pump 16 of this modification is the same as the electrochemical hydrogen pump 16 of the first embodiment, the example of the first embodiment, and the first modification of the first embodiment, except for the above characteristics. There may be.

(Third Modification)
The electrochemical hydrogen pump 16 of this modification is the same as that of the first embodiment, the example of the first embodiment, and the electrochemical hydrogen pump 16 of the first modification of the first embodiment. The cathode gas diffusion layer 2C includes a plurality of ventilation holes 25G of the third metal sheet 22G adjacent to the cathode catalyst layer 3C. In the third metal sheet 22G, at least a part of the opening is closed by a region where the plurality of vent holes 25H of the fourth metal sheet 22H adjacent to the third metal sheet 22G is not provided. In the anode gas diffusion layer 2A, the number of the vent holes 25G is such that at least a part of the openings of the vent holes 25F of the first metal sheet 22F is the second metal sheet 22S. The number of vent holes 25S are closed by a region not provided, less than the number of vent holes 25F of the first metal sheet 22F.

  Since the detailed configuration of the metal sheet 22 of the cathode gas diffusion layer 2C is the same as the configuration of the metal sheet 22 of the anode gas diffusion layer 2A, description thereof is omitted. The third metal sheet 22G and the fourth metal sheet 22H of the cathode gas diffusion layer 2C are anode gas diffusion except for the state in which the third metal sheet 22G and the fourth metal sheet 22H are laminated. Since it is the same as that of the structure of the 1st metal sheet 22F of the layer 2A, and the 2nd metal sheet 22S, description is abbreviate | omitted.

  Although illustration is omitted, for example, the greater the number of completely overlapping vent holes 25G having the same shape (for example, circular shapes with the same diameter) and the vent holes 25H, the more the at least one of the plurality of vent holes 25G. The number of vent holes 25G in which the portion is blocked by the region where the vent holes 25H are not provided is reduced.

  Therefore, in the electrochemical hydrogen pump 16 of this modification, when the third metal sheet 22G and the fourth metal sheet 22H are laminated, the complete overlap between the vent hole 25G and the vent hole 25H is a gas. The diffusion unit 50 is configured to exist in at least a part of the region. Thereby, it is suppressed appropriately that the vent hole 25G of the third metal sheet 22G is closed.

  As described above, the electrochemical hydrogen pump 16 according to the present modification can reduce a decrease in gas diffusibility of the cathode gas diffusion layer 2C as compared with the case where the cathode gas diffusion layer 2C is configured in the same manner as the anode gas diffusion layer 2A. Specifically, when the plurality of vent holes 25G of the third metal sheet 22G of the cathode gas diffusion layer 2C are closed, the gas diffusibility of the cathode gas diffusion layer 2C is lowered. Here, the cathode gas diffusion layer 2C is less susceptible to deformation due to the differential pressure between the cathode and anode of the electrochemical hydrogen pump 16 than the anode gas diffusion layer 2A. For this reason, among the plurality of vent holes 25G in the cathode gas diffusion layer 2C, the number of the vent holes 25G in which at least a part of the openings are closed by the region where the plurality of vent holes 25H are not provided is defined as the anode By reducing at least a part of the plurality of vent holes 25F in the gas diffusion layer 2A compared to the number of vent holes 25F closed by the region where the plurality of vent holes 25S are not provided, A decrease in gas diffusibility of the cathode gas diffusion layer 2C is reduced.

  The shape and arrangement of the vent holes 25G of the third metal sheet 22G and the vent holes 25H of the fourth metal sheet 22H are merely examples, and are not limited to this example.

  The electrochemical hydrogen pump 16 of this modification is the same as the electrochemical hydrogen pump 16 of the first embodiment, the example of the first embodiment, and the first modification of the first embodiment, except for the above characteristics. There may be.

(Second Embodiment)
[Device configuration]
7A and 7B are cross-sectional views of an example of an anode gas diffusion layer of the electrochemical hydrogen pump according to the second embodiment. 7A and 7B show a cross section of a part of the laminate 20 of the anode gas diffusion layer 2A. Note that, as described above, the first metal sheet 22F and the second metal sheet 22S are provided in the portion of the laminate 20 adjacent to the anode catalyst layer 3A. In FIGS. 7A and 7B, these are the same. Illustration of the first metal sheet 22F and the second metal sheet 22S is omitted.

  8A, 8B, and 8C are views in plan view of an example of a metal sheet of a laminate of anode gas diffusion layers.

  The electrochemical hydrogen pump 16 of the present embodiment includes a plurality of electrochemical hydrogen pumps 16 according to any one of the first embodiment, the example of the first embodiment, and the first to third modifications of the first embodiment. Among the metal sheets 22, at least one metal sheet 22 includes a communication path 23 that connects the through holes 21.

  Specifically, as illustrated in FIGS. 7A and 7B, the stacked body 20 includes a metal sheet 22 having a plurality of through holes 21 through which gas passes. In addition, at least one metal sheet 22 among the plurality of metal sheets 22 of the laminate 20 includes a communication path 23 that communicates the through holes 21 with each other.

  The laminated body 20 includes a metal sheet 22 having a plurality of through holes 21, and at least one metal sheet 22 includes any communication path 23 that connects the through holes 21 to each other. Good.

  In the example shown in FIG. 7A, both ends of the through-hole 21 and the communication path 23 constituting the gas flow path (hereinafter referred to as a reference gas flow path) extending in the direction penetrating the laminate 20 and the reference gas flow path are branched. The laminated body 20 is provided with a communication path 23 constituting a gas flow path extending in a direction parallel to the main surface of the laminated body 20 so as to reach the adjacent reference gas flow path. Thereby, the connecting path 23 connects the through holes 21 of the metal sheet 22 adjacent to the metal sheet 22 provided with the connecting path 23.

  In the example shown in FIG. 7B, through-holes 21 constituting a through passage extending in a direction penetrating the stacked body 20 in a gas passage extending in a staircase shape (hereinafter referred to as a staircase gas flow passage), and a staircase gas The laminated body 20 is provided with a communication path 23 that connects the through paths among the flow paths. Thereby, the connecting path 23 connects the through holes 21 of the metal sheet 22 adjacent to the metal sheet 22 provided with the connecting path 23.

  When the laminate 20 is viewed in plan, for example, as shown in FIG. 8A, a plurality of through holes 21A are formed in a matrix (lattice) at equal intervals in the vertical and horizontal directions in the metal sheet 22A of the laminate 20. May be. The shape of the through hole 21A may be any shape. The through hole 21A may be, for example, a round hole having a diameter of about several tens of μm. As a material of the metal sheet 22A, for example, stainless steel or titanium can be used, but is not limited thereto. Note that the metal sheet 22A of FIG. 8A does not include the above communication path.

  Further, as shown in FIG. 8B, a plurality of through holes 21 </ b> B may be formed in the metal sheet 22 </ b> B of the laminate 20 at equal intervals in the vertical and horizontal directions. The shape of the through hole 21B may be any shape. The through hole 21B may be, for example, a round hole having a diameter of about several tens of μm. As a material of the metal sheet 22B, for example, stainless steel or titanium can be used, but is not limited thereto.

  In the example shown in FIG. 8B, when the centers of adjacent through holes 21B are connected, the through holes 21B are arranged vertically and horizontally so as to form a rhombus S indicated by a two-dot chain line. In this example, the communication path 23B is formed so as to be an opening that obliquely connects the centers PB of the adjacent rhombus S. Moreover, it can be said that the communication path 23B extends in a direction parallel to the first direction in which the through holes 21B are connected without crossing the communication path 23B. Further, the connecting path 23B is a straight line connecting adjacent through holes 21B having longer separation distances (through holes 21B adjacent in the vertical direction and the horizontal direction) among the through holes 21B adjacent in a direction different from the first direction. It can also be said that the opening is formed to connect the midpoints (PB). For example, when laminating the metal sheet 22B and the metal sheet 22A, the through hole 21B and the connection are formed so that the through hole 21A and the through hole 21B overlap and the through hole 21A and the both ends of the communication path 23B overlap. The path 23B is arranged. Therefore, in this case, the communication path 23B can connect the through holes 21A.

  The communication path 23B may have any shape. For example, when the through hole 21B is a round hole having a diameter of about several tens of μm, the connecting path 23B may be a slit having a width of about several tens of μm.

  Further, as shown in FIG. 8C, a plurality of through holes 21 </ b> C may be formed in the metal sheet 22 </ b> C of the stacked body 20. The shape of the through hole 21C may be any shape. The through hole 21C may be, for example, a round hole having a diameter of about several tens of μm. As a material of the metal sheet 22C, for example, stainless steel or titanium can be used, but is not limited thereto.

  In the example shown in FIG. 8C, when the centers of adjacent through holes 21C are connected without crossing the connecting path 23C, the through holes 21C are arranged vertically and horizontally so as to form an inclined straight line L indicated by a two-dot chain line. Has been. In this example, the communication path 23C is formed to be an opening that horizontally connects two intermediate points PC when a straight line that connects the through holes 21C adjacent in the horizontal direction is divided into three equal parts. For example, when the metal sheet 22A and the metal sheet 22C are stacked, the through hole 21C and the communication path are formed so that the through hole 21A and the through hole 21C overlap and the through hole 21A and the both ends of the communication path 23C overlap. 23C is arranged. Therefore, in this case, the communication path 23C can communicate the through holes 21A.

  The connecting path 23C may have any shape. For example, when the through hole 21C is a round hole having a diameter of about several tens of μm, the communication path 23C may be a slit having a width of about several tens of μm.

  As described above, the laminate 20 of the anode gas diffusion layer 2A can diffuse the anode gas more uniformly than in the past. That is, when the stacked body 20 includes the communication path 23, the anode gas passing through the stacked body 20 can be sent not only in one direction but also in any direction. Then, the flow direction of the anode gas in the stacked body 20 can be arbitrarily set by stacking the metal sheets 22 having different arrangement patterns of the communication paths 23 on the stacked body 20. Thereby, the gas diffusibility of the anode gas diffusion layer 2A is improved.

  In addition, what kind of combination of the metal sheet 22 from which the arrangement pattern of the connection path 23 differs may be sufficient. For example, the metal sheet having a different arrangement pattern from the metal sheet 22C may be a metal sheet in which the position of the communication path 23C is shifted laterally, or may be the metal sheet 22B.

  Further, for example, when the anode gas is introduced into the through hole 21 of the laminated body 20 of the anode gas diffusion layer 2A through a gas flow path of a flow path member (not shown), the laminated body 20 does not include the above communication path. In addition, the anode gas does not flow into the through hole 21 of the laminate 20 of the anode gas diffusion layer 2A located on the vertical line of the portion where the gas flow path of the flow path member is not provided, and the gas of the anode gas diffusion layer 2A does not flow. Diffusion may be uneven. However, in the anode gas diffusion layer 2A of the electrochemical hydrogen pump 16 of the present embodiment, the anode gas is caused to flow also into the through hole 21 of the laminate 20 of the anode gas diffusion layer 2A via the communication path 23 described above. Therefore, nonuniform gas diffusion in the anode gas diffusion layer 2A can be suppressed.

  As described above, since the gas diffusibility of the anode gas diffusion layer 2A is improved, an increase in the reaction overvoltage of the electrochemical hydrogen pump 16 can be suppressed. That is, an increase in reaction resistance (reaction overvoltage) when hydrogen in the anode gas is dissociated into protons and electrons, that is, an increase in power consumption required for the hydrogen compression operation of the electrochemical hydrogen pump 16 is suppressed more than in the past. .

  Moreover, the contact area between the anode catalyst layer 3A and the metal sheet 22 increases as the number of the communication paths 23 in the metal sheet 22 of the laminate 20 of the anode gas diffusion layer 2A decreases. Here, as shown in FIG. 4, the first metal sheet 22F adjacent to the anode catalyst layer 3A does not include such a communication path, and therefore, between the first metal sheet 22F and the anode catalyst layer 3A. The contact area increases as compared with the case where the anode catalyst layer 3A is adjacent to the metal sheet having the communication path. Therefore, it is possible to appropriately reduce the diffusion resistance between the first metal sheet 22F and the anode catalyst layer 3A.

  Further, when the number of communication paths of the metal sheet 22 of the laminate 20 of the anode gas diffusion layer 2A is increased, variation in fluid resistance in the surface of the metal sheet 22 tends to increase. For example, when an area with many connecting paths and an area with no connecting areas are mixed in the plane of the metal sheet 22, the opening area of the connecting path 23 is larger than that of the through hole 21, so the former area becomes the latter area. Compared to fluid resistance. Then, gas flows more easily in the former area than in the latter area. For this reason, if the metal sheet 22 having a large number of communication paths 23 is in contact with the anode catalyst layer 3A, it is possible to prevent the gas from being uniformly supplied from the anode gas diffusion layer 2A to the entire area of the anode catalyst layer 3A. There is sex. However, in the anode gas diffusion layer 2A of the electrochemical hydrogen pump 16 of the present embodiment, such a possibility is caused by the first metal sheet 22F not having such a communication path being in contact with the anode catalyst layer 3A. Reduced.

  The electrochemical hydrogen pump 16 of the present embodiment is the same as that of the first embodiment, the example of the first embodiment, and any one of the first modification to the third modification of the first embodiment except for the above characteristics. The chemical hydrogen pump 16 may be the same.

  Moreover, the shape and dimension of the above through-hole 21 and the connection path 23 are illustrations, Comprising: It is not limited to this example.

(First embodiment)
FIG. 9 is a cross-sectional view of an example of the anode gas diffusion layer of the electrochemical hydrogen pump according to the first example of the second embodiment. FIG. 9 shows a partial cross section of the laminate 20 of the anode gas diffusion layer 2A. Note that, as described above, the first metal sheet 22F and the second metal sheet 22S are provided in the portion of the stacked body 20 adjacent to the anode catalyst layer 3A. In FIG. Illustration of the metal sheet 22F and the second metal sheet 22S is omitted.

  In the electrochemical hydrogen pump 16 of the present example, in the electrochemical hydrogen pump 16 of the second embodiment, the communication path 23 is provided on the same metal sheet 22D adjacent to the metal sheet 22 provided with the communication path 23. The through hole 21LD and the through hole 21RD communicate with each other. That is, the connecting path 23 connects the left through hole 21LD and the right through hole 21RD that exist in the same metal sheet 22D below the metal sheet 22 provided with the connecting path 23. The through hole 21LD and the through hole 21RD are biased in the direction parallel to the main surface of the stacked body 20 by the length of the communication path 23.

  Moreover, as shown in FIG. 9, the metal sheet 22U above the metal sheet 22 provided with the communication path 23 may include a through hole 21U immediately above the through hole 21LD. In this case, the communication path 23 connects the through hole 21U and the through hole 21RD. The metal sheet 22U above the metal sheet 22 provided with the communication path 23 may include a through hole (not shown) immediately above the through hole 21RD. In this case, the communication path 23 connects the through hole directly above and the through hole 21LD.

  The laminated body 20 of the anode gas diffusion layer 2 </ b> A includes the above-described communication path 23, so that the anode gas passing through the laminated body 20 is not only transmitted through the laminated body 20, but also with the main surface of the laminated body 20. It can also be sent in parallel directions. Therefore, the gas diffusibility of the anode gas diffusion layer 2A is improved.

  The electrochemical hydrogen pump 16 of the present embodiment may be the same as the electrochemical hydrogen pump 16 of the second embodiment except for the above features.

(Second embodiment)
FIG. 10 is a cross-sectional view of an example of the anode gas diffusion layer of the electrochemical hydrogen pump according to the second example of the second embodiment. FIG. 10 shows a partial cross section of the laminate 20 of the anode gas diffusion layer 2A. Note that, as described above, the first metal sheet 22F and the second metal sheet 22S are provided in the portion of the stacked body 20 adjacent to the anode catalyst layer 3A. In FIG. Illustration of the metal sheet 22F and the second metal sheet 22S is omitted.

  The electrochemical hydrogen pump 16 of this example is the electrochemical hydrogen pump 16 of the second embodiment or the first example of the second embodiment. The communication path 23 is adjacent to the metal sheet 22 provided with the communication path 23. The through holes 21U and the through holes 21D provided in the different metal sheets 22U and 22D are connected to each other. That is, the connecting path 23 connects the through hole 21U of the upper metal sheet 22U of the metal sheet 22 provided with the connecting path 23 and the through hole 21U of the lower metal sheet 22D. The through hole 21U and the through hole 21D are biased in the direction parallel to the main surface of the stacked body 20 by the length of the communication path 23.

  The laminated body 20 of the anode gas diffusion layer 2A includes the above-described communication path 23, so that the gas passing through the laminated body 20 is not only in the direction penetrating the laminated body 20, but also in parallel with the main surface of the laminated body 20. Can be sent in any direction. Therefore, the gas diffusibility of the anode gas diffusion layer 2A is improved.

  The electrochemical hydrogen pump 16 of the present embodiment may be the same as the electrochemical hydrogen pump 16 of the second embodiment or the first embodiment of the second embodiment except for the above features.

(Modification)
FIG. 11 is a cross-sectional view of an example of an anode gas diffusion layer of an electrochemical hydrogen pump according to a modification of the second embodiment. FIG. 11 shows a partial cross section of the laminate 20 of the anode gas diffusion layer 2A. Note that, as described above, the first metal sheet 22F and the second metal sheet 22S are provided in the portion of the stacked body 20 adjacent to the anode catalyst layer 3A. In FIG. Illustration of the metal sheet 22F and the second metal sheet 22S is omitted.

  The electrochemical hydrogen pump 16 of the present modification includes a first aspect-second aspect, an example of the first embodiment, a first modification of the first embodiment-a third modification, a second embodiment, and a first embodiment. In the electrochemical hydrogen pump 16 of any one of the first to second examples of the second embodiment, the laminate 20 of the anode gas diffusion layer 2A includes a metal sheet 222 of a metal sintered body that diffuses gas.

  The metal sheet 222 of the metal sintered body is obtained by, for example, sintering metal powder, and has a porous structure including the skeleton part 54 and the plurality of hole parts 53. The air holes 53 are spaces having a diameter of about several tens of μm (for example, about 50 μm) and communicate with each other. Thereby, when the anode gas passes through the metal sheet 222 in the thickness direction, the anode gas can be diffused. Note that the metal sheet 222 is subjected to a smooth surface treatment.

  As described above, in the electrochemical hydrogen pump 16 of the present modification, the laminate 20 of the anode gas diffusion layer 2A includes the metal sheet 222 of the metal sintered body, so that the laminate 20 converts the metal sheet of the metal sintered body. Without providing it, it becomes easier to ensure the gas permeability and gas diffusibility required for the anode gas diffusion layer 2A than in the case of a plurality of metal steel plates provided with ventilation holes.

  The electrochemical hydrogen pump 16 of this modification is the same as the first embodiment, the example of the first embodiment, the first modification of the first embodiment-the third modification, the second embodiment, and the second embodiment, except for the above features. It may be the same as the electrochemical hydrogen pump 16 in any one of the first embodiment to the second embodiment of the second embodiment.

  In addition, 1st Embodiment, Example of 1st Embodiment, 1st modification of 1st Embodiment-3rd modification, 2nd Embodiment, 1st Example of 2nd Embodiment-2nd Example, and Modifications of the second embodiment may be combined with each other as long as they do not exclude each other.

  In addition, many modifications and other embodiments of the disclosure are apparent to those skilled in the art from the foregoing description. Accordingly, the foregoing description is to be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the disclosure. Details of the structure and / or function may be substantially changed without departing from the spirit of the present disclosure.

  One aspect of the present disclosure can be used for an electrochemical hydrogen pump that can reduce the possibility of breakage of an electrolyte membrane pressed against an anode gas diffusion layer due to a differential pressure between a cathode and an anode.

1A: 1st plate 1C: 2nd plate 2A: Anode gas diffusion layer 2C: Cathode gas diffusion layer 3A: Anode catalyst layer 3C: Cathode catalyst layer 4: Electrolyte membrane 7: Cathode chamber 8: Anode chamber 9: On-off valve 10: High-pressure hydrogen tank 11: Anode inlet pipe 12: Cathode outlet pipe 13: Voltage applicator 14A: Gas flow path 14C: Gas flow path 15: Membrane electrode assembly (MEA)
16: Electrochemical hydrogen pump 20: Laminate body 21: Through hole 21A: Through hole 21B: Through hole 21C: Through hole 21D: Through hole 21LD: Through hole 21RD: Through hole 21U: Through hole 22: Metal sheet 22A: Metal sheet 22B: Metal sheet 22C: Metal sheet 22D: Metal sheet 22F: First metal sheet 22S: Second metal sheet 22G: Third metal sheet 22H: Fourth metal sheet 22U: Metal sheet 23: Connection path 23B: Communication path 23C: Communication path 25E: Edge portion 25F: Vent hole 25S: Vent hole 25G: Vent hole 25H: Vent hole 27A: Portion where the openings overlap 27C: Portion where the openings overlap 50: Gas diffusion portion 53: Hole portion 54: Skeletal part 100: Region 125E: Edge part 125F: Vent hole 125S: Vent hole 125G: Vent hole 125H Vent 127AA: first portion 127AB: second portion 127AC: third portion 127CA: first portion 127CB: second portion 127CC: third portion 222: metal sheet

Claims (9)

An electrolyte membrane comprising a pair of main surfaces;
A cathode catalyst layer provided on one main surface of the electrolyte membrane;
An anode catalyst layer provided on the other main surface of the electrolyte membrane;
A cathode gas diffusion layer provided in the cathode catalyst layer;
An anode gas diffusion layer provided in the anode catalyst layer;
A voltage applicator for applying a voltage between the cathode catalyst layer and the anode catalyst layer;
With
The anode gas diffusion layer includes a laminate of a plurality of metal sheets provided with a plurality of vent holes,
In the anode gas diffusion layer, the arrangement positions of the plurality of ventilation holes of the first metal sheet adjacent to the anode catalyst layer and the arrangement of the plurality of ventilation holes of the second metal sheet adjacent to the first metal sheet. The installation position has shifted,
A part of the opening of the vent hole of the first metal sheet overlaps with the opening of the vent hole of the second metal sheet,
The remaining portion of the opening of the vent hole of the first metal sheet is closed by an area where the vent hole of the second metal sheet is not provided.   The electrochemical hydrogen pump according to claim 1, wherein the thickness of the first metal sheet is smaller than the thickness of the electrolyte membrane. The area of the portion where the opening of the vent hole of the first metal sheet and the opening of the vent hole of the second metal sheet overlap is 8 × circularity × (tensile strength of the electrolyte membrane) × (thickness of the electrolyte membrane) ^The electrochemical hydrogen pump according to claim 1 or 2, which is smaller than ² / (3 × (theoretical breaking pressure of the electrolyte membrane) × (3 + Poisson's ratio of the electrolyte membrane)). The cathode gas diffusion layer includes a laminate of a plurality of metal sheets provided with a plurality of vent holes,
In the cathode gas diffusion layer, at least a part of the openings of the plurality of vent holes of the third metal sheet adjacent to the cathode catalyst layer has a plurality of passages of the fourth metal sheet adjacent to the third metal sheet. The total area covered by the regions where no pores are provided is that, in the anode gas diffusion layer, the openings of the plurality of vent holes of the first metal sheet are the plurality of openings of the second metal sheet. The electrochemical hydrogen pump according to any one of claims 1 to 3, wherein the electrochemical hydrogen pump is smaller than a total area covered by a region where pores are not provided. The cathode gas diffusion layer includes a laminate of a plurality of metal sheets provided with a plurality of vent holes,
In the cathode gas diffusion layer, among the plurality of vent holes of the third metal sheet adjacent to the cathode catalyst layer, at least a part of the opening of the fourth metal sheet adjacent to the third metal sheet. The number of vent holes in the third metal sheet, which is blocked by a region where a plurality of vent holes are not provided, is the number of vent holes in the first metal sheet in the anode gas diffusion layer. At least a part of the opening is less than the number of ventilation holes of the first metal sheet, which is blocked by a region where the plurality of ventilation holes of the second metal sheet are not provided. 4. The electrochemical hydrogen pump according to any one of 3 above.   The electrochemical hydrogen pump according to any one of claims 1 to 5, wherein at least one of the plurality of metal sheets includes a communication path that connects the through holes.   The electrochemical hydrogen pump according to claim 6, wherein the communication path connects through holes provided in the same metal sheet adjacent to the metal sheet provided with the communication path.   The electrochemical hydrogen pump according to claim 6 or 7, wherein the communication path connects through holes provided in different metal sheets adjacent to the metal sheet provided with the communication path.   The electrochemical hydrogen pump according to claim 1, wherein the laminate includes a metal sheet of a metal sintered body that diffuses gas.

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